The present invention relates to an apparatus and method for supplying encoded data, derived from variable length encoding of video data, in bitstream form.
In conventional video encoding apparatus, such encoded data is written directly into a first in first out (FIFO) memory and is read from the FIFO memory as a bitstream. A cycle time, taken to-read from a FIFO memory encoded data that is derived from variable length encoding of video data for every processing unit, is fixed correspondingly to the largest of bit quantities of the encoded data assumed in the processing unit.
Such a conventional configuration is problematic. For example, whether bitstreams are output with efficiencies or with inefficiencies depends upon the total bit quantity of encoded data generated by variable length encoding. A write operation cycle time, taken to write encoded data in a FIFO memory, varies widely depending on the quantity of video data per processing unit of the write operation. On the other hand, as described above, a read operation cycle time, taken to read the encoded data from the FIFO memory, is fixed correspondingly to the largest bit quantity of the write operation processing unit. This means that, at the time of reading encoded data having a bit quantity smaller than the assumed largest bit quantity from a FIFO memory, there is produced a difference between the set cycle time and actual read time, therefore wasting time. This prevents a rise in the system processing efficiency. When trying to improve the processing efficiency by a reduction of the time to be wasted, this requires an increase in the memory bitwidth or an increase in the operating frequency therefore resulting in an increase in the system cost.